The clearer ones I can tell because there are indicators. A cup breaking, a horse bucking its ride off in a particular location, a bluebird singing on a window sill when I wake up, little pieces of imagery like that show up in the dream, then if I see those exact moments in real life, I know the rest is coming to pass.

[ it's vague, but it's something she's had many years to learn to discern. At the very least, she's sure enough this is happening now. ]